α-1-Antichymotrypsin, a Serine Protease Inhibitor, is a Component of the Amyloid Deposits in Alzheimer’s Disease

Abstract

Alzheimer’s disease brains are characterized by three neuropathological lesions: neuritic plaques, neurofibrillary tangles, and vascular amyloid deposits. Neuritic plaques are spherical in shape and consist of a core of extracellular amyloid filaments surrounded by a halo of degenerating nerve cell processes. The neurites frequently contain a class of abnormal protein fibers termed paired helical filaments. These are composed of two helically-wound, ~10 nm filaments, that are immunologically related to the cytoskeletal proteins of the neuron (for review, see Selkoe, 1986). The same paired helical filaments can also be found in large aggregates, called neurofibriliary tangles, in the cell bodies of certain neurons. The third type of proteinaceous deposit in Alzheimer’s disease brain consists of amyloid filaments similar to those in the cores of neuritic plaques, and occurs in the walls of meningeal and intracortical blood vessels.